Add a basic test that attempts to send a DNS request to the configured
servers. This should catch e.g. firewalled hosts being configured to use
public nameservers that they can't even reach.
Cleaned up reporting of the commands that were run. This is intended to
make it easier for a system or network administrator to understand the
specific tests being run, and the relevance of their results.
Attempt to determine whether this network provides proxy auto-detection
(WPAD/autoproxy/PAC), and if so, diagnose whether we get good
information and make use of it.
Improve reporting of suggested actions to take.
Shorten curl connect timeouts so we fail faster. Assuming 10 seconds
without completing a TCP connection is long enough to conclude that
something's wrong, and move on to diagnostics more quickly.
Brett T. Warden